[MUSIC] So this lecture will talk about the Arduino schematics. The schematics of the actual Arduino board. This is definitely, somewhat advanced. We’re not going to be modifying the schematics but it’s still very useful to look at. Because understanding schematics, being able to read them, is a very useful skill. Because often, I find, whenever I make any new design the first thing I do is look for people who have already made similar designs, right. So I go on the internet and look around, and has anybody ever done anything like this. And you find DIY projects, do it yourself projects that are up there online. And the traditional way to convey a hardware design is to draw you a schematic. They say, look, here's how we've wired everything. That's what a schematic is, it's a diagram of what the components are on the device and how they're wired together. I said, you can copy that. So, often I find myself looking at schematics and then copying them. Implementing, wiring things together according to schematic. So you have to be able to read these schematics in order to do that. So, it's a very useful thing to be able to do, so we'll look at doing arduino schematic a little bit, since it's an open source schematic and we can do that. So this is the schematic for the Arduino UNO revision three, rev three, which is what you probably are using. The Arduino designs are open source, so this hardware schematic is open source. And you can download this off arduino.cc website. You could build your own. You could take that schematic and design your own circuit, wire it together if you wanted to. Now you'll notice, this is a little bit smaller to read, but it's got a lot of different components. We won't go through everything, but we'll go through sort of the big pieces in there, just to describe what they are and how they relate to the board. Because all of the components that you see in this schematic are on the physical development board that you have. So they're all on there. Notice one thing too, that the layout here, the layout that you see them draw on the schematic has nothing to do with how they are laid out on the actual board, right? When they lay them out on the physical board, the layout is done the placement, placing the parts, is done in such a way to make it compact. Where on a screen when you see a schematic, you're not necessarily worried about compactness, you want it to be more readable. Right? So, it's laid out in a completely different fashion in the schematic than it actually is on the physical board. Now if you want to see the actual board layout, the eagle files, the cat files for that, they are available on Arduino.cc and they are harder to read, but you can look at that. But this is not that. This is just a wiring schematic that shows you what components should be connected to what. And what pins should be connected to what pins. So, let's look at it in a little more detail. Okay, so if you look at the schematic, we've highlighted a few interesting things here. First things we've highlighted are the processors. So like we said, there are two microcontrollers on this device. There's the ATmega328, which is the main one that you're gonna be programming. And then there's the ATmega16U2 that deals with the USB connection. So you can see both of those are highlighted in the picture And actually, from the look of it, it looks like the ATmega16U2 is bigger. It's not bigger [LAUGH]. This is not drawn to scale. So the ATmega16U2 is actually a smaller chip on the board. But that doesn't matter. It's bigger because the text is bigger inside the box. And you'll notice that each one of these components, they label each one of the pins. So you can see their names for each one of the pins that tell you what pins are being wired to what. Also, you could see the pins to the board, so the Adruino board, are also highlighted. So the power pins, the analog in pins, and the digital i o pins. You can see all those wired there, too, or highlighted there, too. Those relate directly to components that you see on the board, that we saw on the board already. Now in addition to these, what do we have. Here's some more interesting parts. Power connector, so remember we saw the power connector on the board, there it is highlighted. The ICSP headers, ICSP1 ICSP2 those two headers that are used for programming the firmware on the two processors, those are highlighted there. The USB connector you can see that. And just for a reference sake, cuz he had to make a 328 again. So those are most of the big parts that are on the board and that you can see in the schematic. There are a bunch of little parts in there, LEDs and things like this, resistors, little components too, but we're not gonna go enumerate all of them. But the idea though, is that the whole point of the schematic is to show you how everything is wired together. Thank you. [MUSIC]